In theory, age shouldn't be a determinant of an IBW figure from middle age onwards because the height of a human generally stays constant and does not go through the growth in height apparent in young ages. It is actually expected for human males and females to lose 1.5 and 2 inches in height respectively by age 70. Therefore, the only variables acting on body weight are muscle mass and body fat, and the many different factors associated with the two,
such as illness, diet, and exercise. However, it is important to remember that as people age, lean muscle mass decreases and accumulation of excess body fat is easier. This is a natural process of human biology over a lifespan, though actions can be taken to thwart it such as controlling for important variables such as diet, exercise, stress, and sleep.
Generally, females weigh less than males even though they are prone to carry more body fat.. The physical, genetic makeup of a male body naturally has more muscle mass, which is heavier than fat. Not only that, but women are less dense (physically); they have lower bone density. Last but not least, males tend to be taller than females.
Height becomes the main factor in an IBW figure. Obviously, the taller the person, the more muscle mass and body fat required to fill it out, resulting in more weight. A male at a similar height to a female should weigh about 10-20% heavier.
Healthy BMI Range
The World Health Organization's (WHO) recommended healthy BMI range is 18.5 - 25 for both male and female.
BMI is a commonly used metric in determining IBW. It is widely used in the medical field as a quick indicator of possible health complications. Generally, the higher the BMI, the higher the chance a person has to suffer health problems from obesity and diabetes, to heart disease and many more. It is a indicator used by doctors to advice their patients of potential health problems, especially if there is a noticeable progressive increase in their BMI,
and is currently the official metric for classifying individuals according to different obesity levels.